The present invention relates to a decolorizable toner, and more particularly to a near infrared ray-decolorizable toner which can make an electric latent image or an electric signal used in electrophotography, electrostatic recording materials and the like visible.
In recent years the reuse or recyle of used papers has been studied in order that forest resources can be protected and that used papers can be diminished from cities. As a part of the reuse or recyle of used papers, the reuse of used papers such as copied paper, printed paper and used facsimile paper which are discarded in an office of enterprise, has been studied.
There is an attempt to join a paper-manufacturing company in one enterprise so that used papers can be reused or recycled by collecting and dissolving the used papers to produce regenerated paper in the paper-manufacturing company. However, since most of these used paper are generally confidential papers of the enterprise, it is very difficult that the used papers are collected to produce regenerated paper in a paper-collected manufacturing company outside the enterprise. Also, since recorded figures or printed images of the used papers cannot be easily erased, the used papers are required to be burned or crushed for dumping. Therefore, it has been thought that the used papers cannot be probably actually reused. Also, although the recycle of the used papers which are previously crushed by using a paper-shredder has been studied, there is a defect that regenerated paper made of the crushed papers cannot be used as, for instance, specialty papers for communication since the regenerated paper generally has small mechanical strength.
As a toner which overcomes the above problems, we have developed a decolorizable toner containing a near infrared ray-decolorizing recording material which is decomposed and decolorized by absorbing near infrared rays.
When an electrostatic copying is carried out with the decolorizable toner, images or printed figures recorded on a recording paper can be easily decolorized only by the irradiation of near infrared rays, and therefore, the recording paper can be reused. Also, when the used recording paper is disposed, the recorded images or printed figures can be decolorized by the irradiation of near infrared rays, and therefore, there are many advantages such that the collected used recording papers can be reused at the same time that the transpiration of secret matters described in confidential papers can be prevented.
The decolorizable toner, however, has disadvantages in terms of decolorizing of the near infrared ray-decolorizing material when the decolorizable toner is exposed to natural light during the production or storage of the decolorizable toner since the natural light contains a light which denaturalizes the near infrared ray-decolorizing material and a sensitizer for decolorizing the near infrared ray-decolorizing material contained in the above decolorizable toner.
An object of the present invention is to provide a decolorizable toner having excellent light stability during the production or storage of the decolorizable toner, and forming images having excellent light resistance.
A further object of the present invention is to provide a decolorizable toner having excellent decolorizing property.
These and other objects of the present invention will become apparent from the description hereinafter.